Design of metamorphic clamping mechanism for imitating crocodiles

YI Xianying; ZHOU Zupeng; PENG Jiansheng; WU Zhe

doi:10.16578/j.issn.1004.2539.2025.08.011

Abstract：[Objective]To achieve enveloping and stable grasping of spherical-like fruits,a crocodile-inspired metamorphic clamping mechanism was designed by combining the excellent characteristics of crocodiles with metamorphic mechanisms.[Methods]Firstly,the reverse engineering technology was employed to perform the three-dimensional reconstruction of a Cuban crocodile skull model.Based on the morphological features of the crocodile's upper jaw,surface fitting was conducted,and char-acteristic points were extracted to design a crocodile-inspired end effector.Secondly,addressing the two motion characteristics of crocodiles—the generation of tearing forces during the death roll and the instantaneous increase in bite force when biting prey,a direction metamorphic module and a force metamorphic module were designed for the crocodile-inspired metamorphic clamp-ing mechanism based on the graph theory.Subsequently,the crocodile-inspired end effector and the metamorphic modules were integrated to construct the crocodile-inspired metamorphic clamping mechanism.Finally,the adjacency matrix method was used to analyze the topological structure transformation process of the metamorphic mechanism,followed by theoretical analyses of kinematics and statics,leading to the completion of simulations and the fabrication of a prototype.[Results]Simulation and test results verify the feasibility and grasping stability of the proposed mechanism.